1. Field of the Invention
The present invention relates to a method and apparatus for detecting the presence of media. More particularly, the present invention relates to a method and apparatus for detecting the presence of media based on a detection of light intensity.
2. Description of the Related Art
Media manipulation and sensing apparatuses typically include a media detector for detecting for the presence of media. The media manipulation and sensing apparatuses typically include media trays, picking mechanisms to move the media from the media trays, and mechanisms thereafter to perform some manipulation or sensing of the media. A media detector may be positioned near the picking mechanism and detect the presence of the media by the picking and feeding of the media past the media detector, such that upon the initiating of a picking and feeding operation the media detector would be able to detect whether a media is present.
However, it would be advantageous to know whether media is present prior to the initiating of the printing and feeding operation or while another media is being printed upon or fed.
Typically, the presence of media in a media manipulation or sensing apparatus is detected by mechanical media detectors, as illustrated by Kikuchi et al., U.S. Pat. No. 4,690,577, where a media entering a printing area moves a mechanical lever and the movement of the lever is detected, or through optical media detectors, as illustrated by Minerd et al., U.S. Pat. No. 4,540,887, where a reflective or translucent property of a media is used to detect the media""s presence. Similar optical media detection has also been disclosed in Courtney et al., U.S. Pat. No. 5,139,339, in which the media detector also detects the media type.
Previously, the sensing of media presence by a media detector was accomplished by several different techniques. Some techniques included having a highly reflective material in the media path, such that light illuminating the media path at a precise angle would be highly reflected to the specularly arranged sensor when media was not present. However, with the current use of highly reflective transparency media, this technique would not work as the specularly arranged sensor may indicate a lack of media presence when the media present is a transparency.
Alternative techniques included placing a light redirecting surface beneath the media path, such that when media was not present the specularly arranged sensor would only measure a negligible amount of light. An example of this technique would be to have a surface directly beneath the media detector with a surface angle different from the surface angle of a media path. When no media is present, light would be redirected by the differently angled surface, away from the specularly arranged sensor. However, these techniques that use the light redirecting surface are not usually reliable, as light from external sources may infiltrate a light detecting area of the media detector and thus allow enough light to radiate to the specularly arranged sensor to indicate, inaccurately, that media is present. Typically, media detectors are positioned above the media path with spacing therebetween, which undesirably allows for such external light to infiltrate the media detecting area of the media detector.
Further, in a related art, media manipulation or sensing apparatuses may operate in different modes based on the presence of different types of media. A media manipulation or sensing apparatus may operate in a different mode if the media type is of a high glossy type, like a transparency media type, compared to when the media type is of a low glossy type, like plain paper. For example, in a printing environment, certain parameters of printing onto a media are adjusted based upon the media type determination. Typically, in the printing environment, a user must manually indicate to a printing apparatus what type of media is present. Alternatively, some printing systems xe2x80x9cpick,xe2x80x9d or grab, the media and advance it through the printing system, and then determine the type of media, format the parameters for printing thereon, and proceed with printing onto the media. However, these systems are not usually desirable, as the printing system cannot perform the procedure to determine what type of media is being printed on until after advancing the media, which reduces the throughput of media in the printing system. Knowing the media type before picking allows one to adjust certain printing parameters so as to optimize the printing process for that media. This is something that is now done when the user manually indicates to the printing system what type of media is present.
These aforementioned optical methods and apparatuses previously implemented for media detection have also been included in such media type detectors, having multiple sensors detecting an amount of light reflected off a media. In one media type detector, as illustrated in FIG. 1, when light source 10 irradiates media 5, light reflecting off media 5 is detected by diffuse sensor 20 and specular sensor 30. The glossiness of media 5 may be determined by measuring the ratio of the detected diffuse I(D) and specular I(S) light intensities. Glossier papers tend to reflect specularly more than difflusely, thus a media type detecting ratio of I(S)/I(D) can be used to determine the glossiness of media 5, from which the type of media can be determined.
Therefore, the present invention overcomes these aforementioned deficiencies in conventional systems by setting forth a media detector wherein a light blocking mechanism is used in conjunction with a light source and sensor, such that extraneous light will not enter a media detecting area and cause the media detector to generate inaccurate media detection results. In addition, the present invention allows for the placement of the media detector before a picking mechanism, such that it can be determined whether media is present before initiating a picking operation. The present invention can be utilized in combination with a media type detector to detect media type when media is detected.
An object of the present invention is to provide a method and apparatus for detecting the presence of media based on a detection of light intensity.
An additional object of the present invention is to provide a media manipulation apparatus having a media detector including, a first light sensor arranged on a top or bottom side of a media path, and a light blocking mechanism arranged on an opposing side of the media path compared to the arrangement of the first light sensor. The light blocking mechanism blocks light from being detected by the first light sensor when a media is not present on the media path between the first light sensor and the light blocking mechanism. The media manipulation apparatus also includes a determining unit to determine whether the media is present based on a detected light intensity of the first light sensor being effectively zero. apparatus having a media detector including, a first light sensor arranged on a top or bottom side of a media path, and a light blocking mechanism arranged on an opposing side of the media path compared to the arrangement of the first light sensor. The light blocking mechanism blocks light from being detected by the first light sensor when a media is not present on the media path between the first light sensor and the light blocking mechanism. The media sensing apparatus further includes a determining unit to determine whether the media is present based on a detected light intensity of the first light sensor being effectively zero.
Another object of the present invention is to provide a media detector having a first light sensor arranged on a top or bottom side of a media path, and a light blocking mechanism arranged on an opposing side of the media path compared to the arrangement of the first light sensor. The light blocking mechanism blocks the first light sensor from detecting light when a media is not present on the media path between the first light sensor and the light blocking mechanism.
Another object of the present invention is to provide a media detection method for use with a media detector having a light source and a first light sensor to detect a light intensity of light reflecting off of a media that travels on a media path, with the light source and first light sensor being arranged on a top or bottom side of the media path. The media detection method includes blocking the first light sensor from detecting light by using a light blocking mechanism arranged on an opposing side of the media path, compared to the arrangement of the light source and first light sensor, when no media is present in the media path between the first light sensor and the light blocking mechanism, and determining whether the media is present based on an intensity of the first light sensor being effectively zero.
Another object of the present invention is to provide a media detection method for use with a media detector having a light source and a first light sensor to detect a light intensity of light reflecting off of a media that travels on a media path, with the light source and first light sensor being arranged on a top or bottom side of the media path. The media detection method includes blocking the light source from radiating light onto a media path area by using a light blocking mechanism arranged on an opposing side of the media path, compared to the arrangement of the light source and first light sensor, when no media is present in the media path between the light source and the light blocking mechanism, and determining whether the media is present based on an intensity of the first light sensor being effectively zero.